diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/hrtimer.c | 58 | ||||
| -rw-r--r-- | kernel/sched.c | 11 | ||||
| -rw-r--r-- | kernel/sysctl.c | 8 | ||||
| -rw-r--r-- | kernel/time/clockevents.c | 12 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 7 | ||||
| -rw-r--r-- | kernel/timer.c | 51 | ||||
| -rw-r--r-- | kernel/trace/trace_sysprof.c | 3 |
7 files changed, 132 insertions, 18 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index cb8a15c..b675a67 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -43,6 +43,8 @@ #include <linux/seq_file.h> #include <linux/err.h> #include <linux/debugobjects.h> +#include <linux/sched.h> +#include <linux/timer.h> #include <asm/uaccess.h> @@ -193,12 +195,24 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, * Switch the timer base to the current CPU when possible. */ static inline struct hrtimer_clock_base * -switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base) +switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, + int pinned) { struct hrtimer_clock_base *new_base; struct hrtimer_cpu_base *new_cpu_base; + int cpu, preferred_cpu = -1; + + cpu = smp_processor_id(); +#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP) + if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) { + preferred_cpu = get_nohz_load_balancer(); + if (preferred_cpu >= 0) + cpu = preferred_cpu; + } +#endif - new_cpu_base = &__get_cpu_var(hrtimer_bases); +again: + new_cpu_base = &per_cpu(hrtimer_bases, cpu); new_base = &new_cpu_base->clock_base[base->index]; if (base != new_base) { @@ -218,6 +232,40 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base) timer->base = NULL; spin_unlock(&base->cpu_base->lock); spin_lock(&new_base->cpu_base->lock); + + /* Optimized away for NOHZ=n SMP=n */ + if (cpu == preferred_cpu) { + /* Calculate clock monotonic expiry time */ +#ifdef CONFIG_HIGH_RES_TIMERS + ktime_t expires = ktime_sub(hrtimer_get_expires(timer), + new_base->offset); +#else + ktime_t expires = hrtimer_get_expires(timer); +#endif + + /* + * Get the next event on target cpu from the + * clock events layer. + * This covers the highres=off nohz=on case as well. + */ + ktime_t next = clockevents_get_next_event(cpu); + + ktime_t delta = ktime_sub(expires, next); + + /* + * We do not migrate the timer when it is expiring + * before the next event on the target cpu because + * we cannot reprogram the target cpu hardware and + * we would cause it to fire late. + */ + if (delta.tv64 < 0) { + cpu = smp_processor_id(); + spin_unlock(&new_base->cpu_base->lock); + spin_lock(&base->cpu_base->lock); + timer->base = base; + goto again; + } + } timer->base = new_base; } return new_base; @@ -235,7 +283,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) return base; } -# define switch_hrtimer_base(t, b) (b) +# define switch_hrtimer_base(t, b, p) (b) #endif /* !CONFIG_SMP */ @@ -907,9 +955,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, ret = remove_hrtimer(timer, base); /* Switch the timer base, if necessary: */ - new_base = switch_hrtimer_base(timer, base); + new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED); - if (mode == HRTIMER_MODE_REL) { + if (mode & HRTIMER_MODE_REL) { tim = ktime_add_safe(tim, new_base->get_time()); /* * CONFIG_TIME_LOW_RES is a temporary way for architectures diff --git a/kernel/sched.c b/kernel/sched.c index 8ec9d13..8fb88a9 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -240,7 +240,7 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b) hard = hrtimer_get_expires(&rt_b->rt_period_timer); delta = ktime_to_ns(ktime_sub(hard, soft)); __hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta, - HRTIMER_MODE_ABS, 0); + HRTIMER_MODE_ABS_PINNED, 0); } spin_unlock(&rt_b->rt_runtime_lock); } @@ -1155,7 +1155,7 @@ static __init void init_hrtick(void) static void hrtick_start(struct rq *rq, u64 delay) { __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0, - HRTIMER_MODE_REL, 0); + HRTIMER_MODE_REL_PINNED, 0); } static inline void init_hrtick(void) @@ -4397,6 +4397,11 @@ static struct { .load_balancer = ATOMIC_INIT(-1), }; +int get_nohz_load_balancer(void) +{ + return atomic_read(&nohz.load_balancer); +} + #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) /** * lowest_flag_domain - Return lowest sched_domain containing flag. @@ -9029,6 +9034,8 @@ void __init sched_init_smp(void) } #endif /* CONFIG_SMP */ +const_debug unsigned int sysctl_timer_migration = 1; + int in_sched_functions(unsigned long addr) { return in_lock_functions(addr) || diff --git a/kernel/sysctl.c b/kernel/sysctl.c index ce664f9..0e51a35 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -328,6 +328,14 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = &proc_dointvec, }, + { + .ctl_name = CTL_UNNUMBERED, + .procname = "timer_migration", + .data = &sysctl_timer_migration, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, #endif { .ctl_name = CTL_UNNUMBERED, diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 3948fa6..1ad6dd4 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -18,6 +18,7 @@ #include <linux/notifier.h> #include <linux/smp.h> #include <linux/sysdev.h> +#include <linux/tick.h> /* The registered clock event devices */ static LIST_HEAD(clockevent_devices); @@ -253,4 +254,15 @@ void clockevents_notify(unsigned long reason, void *arg) spin_unlock(&clockevents_lock); } EXPORT_SYMBOL_GPL(clockevents_notify); + +ktime_t clockevents_get_next_event(int cpu) +{ + struct tick_device *td; + struct clock_event_device *dev; + + td = &per_cpu(tick_cpu_device, cpu); + dev = td->evtdev; + + return dev->next_event; +} #endif diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index d3f1ef4..2aff39c 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -349,7 +349,7 @@ void tick_nohz_stop_sched_tick(int inidle) if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { hrtimer_start(&ts->sched_timer, expires, - HRTIMER_MODE_ABS); + HRTIMER_MODE_ABS_PINNED); /* Check, if the timer was already in the past */ if (hrtimer_active(&ts->sched_timer)) goto out; @@ -395,7 +395,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { hrtimer_start_expires(&ts->sched_timer, - HRTIMER_MODE_ABS); + HRTIMER_MODE_ABS_PINNED); /* Check, if the timer was already in the past */ if (hrtimer_active(&ts->sched_timer)) break; @@ -698,7 +698,8 @@ void tick_setup_sched_timer(void) for (;;) { hrtimer_forward(&ts->sched_timer, now, tick_period); - hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS); + hrtimer_start_expires(&ts->sched_timer, + HRTIMER_MODE_ABS_PINNED); /* Check, if the timer was already in the past */ if (hrtimer_active(&ts->sched_timer)) break; diff --git a/kernel/timer.c b/kernel/timer.c index faf2db8..54d3912 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -38,6 +38,7 @@ #include <linux/tick.h> #include <linux/kallsyms.h> #include <linux/perf_counter.h> +#include <linux/sched.h> #include <asm/uaccess.h> #include <asm/unistd.h> @@ -605,13 +606,12 @@ static struct tvec_base *lock_timer_base(struct timer_list *timer, } static inline int -__mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) +__mod_timer(struct timer_list *timer, unsigned long expires, + bool pending_only, int pinned) { struct tvec_base *base, *new_base; unsigned long flags; - int ret; - - ret = 0; + int ret = 0 , cpu; timer_stats_timer_set_start_info(timer); BUG_ON(!timer->function); @@ -630,6 +630,18 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) new_base = __get_cpu_var(tvec_bases); + cpu = smp_processor_id(); + +#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP) + if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) { + int preferred_cpu = get_nohz_load_balancer(); + + if (preferred_cpu >= 0) + cpu = preferred_cpu; + } +#endif + new_base = per_cpu(tvec_bases, cpu); + if (base != new_base) { /* * We are trying to schedule the timer on the local CPU. @@ -669,7 +681,7 @@ out_unlock: */ int mod_timer_pending(struct timer_list *timer, unsigned long expires) { - return __mod_timer(timer, expires, true); + return __mod_timer(timer, expires, true, TIMER_NOT_PINNED); } EXPORT_SYMBOL(mod_timer_pending); @@ -703,11 +715,33 @@ int mod_timer(struct timer_list *timer, unsigned long expires) if (timer->expires == expires && timer_pending(timer)) return 1; - return __mod_timer(timer, expires, false); + return __mod_timer(timer, expires, false, TIMER_NOT_PINNED); } EXPORT_SYMBOL(mod_timer); /** + * mod_timer_pinned - modify a timer's timeout + * @timer: the timer to be modified + * @expires: new timeout in jiffies + * + * mod_timer_pinned() is a way to update the expire field of an + * active timer (if the timer is inactive it will be activated) + * and not allow the timer to be migrated to a different CPU. + * + * mod_timer_pinned(timer, expires) is equivalent to: + * + * del_timer(timer); timer->expires = expires; add_timer(timer); + */ +int mod_timer_pinned(struct timer_list *timer, unsigned long expires) +{ + if (timer->expires == expires && timer_pending(timer)) + return 1; + + return __mod_timer(timer, expires, false, TIMER_PINNED); +} +EXPORT_SYMBOL(mod_timer_pinned); + +/** * add_timer - start a timer * @timer: the timer to be added * @@ -1017,6 +1051,9 @@ cascade: index = slot = timer_jiffies & TVN_MASK; do { list_for_each_entry(nte, varp->vec + slot, entry) { + if (tbase_get_deferrable(nte->base)) + continue; + found = 1; if (time_before(nte->expires, expires)) expires = nte->expires; @@ -1307,7 +1344,7 @@ signed long __sched schedule_timeout(signed long timeout) expire = timeout + jiffies; setup_timer_on_stack(&timer, process_timeout, (unsigned long)current); - __mod_timer(&timer, expire, false); + __mod_timer(&timer, expire, false, TIMER_NOT_PINNED); schedule(); del_singleshot_timer_sync(&timer); diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c index e04b76c..f669396 100644 --- a/kernel/trace/trace_sysprof.c +++ b/kernel/trace/trace_sysprof.c @@ -203,7 +203,8 @@ static void start_stack_timer(void *unused) hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hrtimer->function = stack_trace_timer_fn; - hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL); + hrtimer_start(hrtimer, ns_to_ktime(sample_period), + HRTIMER_MODE_REL_PINNED); } static void start_stack_timers(void) |
